In the Academy, Tal had great difficulty with Starfleet training courses, and worked three times as hard as everyone else in order to keep up with her classmates. She believed that she got into Starfleet because she was Bajoran and that her instructors made life a little easier for her for the same reason, as having Bajoran officers in Starfleet was in the Federation's best interest. Despite this she still had to pull all-nighters every night, something that continued on Voyager.

During her time on Voyager, Tal was assigned to Astrometrics under Seven of Nine. By 2376, Celes was a grade three sensor analyst. While on Voyager Tal had severe doubts in her ability to perform her assigned tasks, and her work was being checked and rechecked by her co-workers and superiors due to her many mistakes. As a result, she often worked through the night in order to complete her duties. Her best friend on Voyager was William Telfer, whom she often helped with his hypochondria, he in turn helped her with her task aboard the ship.

In 2376, Seven of Nine singled out Celes to CaptainJaneway as one of three crewmembers who were unable to meet their duties to the required levels. Since Voyager was unable to rotate these crewmembers to another starship with less challenging demands, as would normally be the case, Janeway decided to have the three join her aboard the Delta Flyer on a survey mission. When the Flyer came under attack, Celes helped determine the source and cause of the attack, and remained aboard the Flyer, rather than abandon the captain. (VOY: "Good Shepherd")

Later that year, the USS Voyager was accidentally boarded by an electromagnetic life-form, which caused many power outages. Seven of Nine accused Tal Celes of causing a power shortage in astrometrics by performing a flawed diagnostic. Later Tal was left wandering the corridors of the ship alone for "4 or 5 hours". While wandering alone in the dark she became paranoid and started to believe the ship had been taken over by hostile aliens. She eventually ran into Harry Kim whom she mistook to be either a Borg or a Hirogen. Kim calmed her down and the two of them walked to the temporary command post in main engineering. (VOY: "The Haunting of Deck Twelve")

In 2377, she was brainwashed by the Quarren after they irradiated Voyager and forced the evacuation of its crew. She, along with most of the rest of the crew, spent approximately three weeks in the largest city on Quarra, their memories were altered and they were unaware that they had been kidnapped. On Quarra she worked in a fusion reactor with Mulcahey, they did not know they knew each other from Voyager. (VOY: "Workforce, Part I")

In 2381, Jon and Tal were married in a shipboard ceremony officiated by Captain MacLeod in which Joshua Gunn served as the father of the bride for the ceremony.

On August 20th 2387, Tal gave birth to her and Jon's half Bajoran half Human son Edon Sulu, named for Tal's father.

While on the Prometheus Tal developed a close friendships with Ensign D4 Green and Cadet Erin Denali and came to regard Master Chief Petty Officer Joshua Gunn as a father figure, to whom she eventually revealed some of her past including her parents and paternal grandmother's names.